The present invention relates to a device for cutting elongated profiles into sections. More particularly, the present invention pertains to a device for aligning a raster mark provided on the elongated profile with a saw blade. The proposed device is especially suitable for tubes provided with perforated regions spaced from each other, which tubes are to be cut into sections at predetermined areas between the perforated regions whereby raster marks are provided at certain intervals on the surface of the elongated tube. These raster marks can be formed as projections or depressions extended transversely of the elongation of the tube and can be made as cutouts by stamping-out.
The profiles, subject of the present application, are known as tubes having perforated regions and employed in mufflers in exhaust systems of motor vehicles.
Depending on the system of the muffler, basically on the dimensions and other requirements of the muffler tube certain perforations are provided in the muffler tube, which perforations are usually formed on the periphery of the tube and extend over a predetermined region. The length of this perforated region varies for various exhaust systems and various sizes of the tubes. Furthermore, this perforated region has, depending on the muffler system, a predetermined location relative to the edges of the tube. In order to ensure the position of the perforated region on the tube, this region should be provided at the certain distance from the front and rear end of the tube.
Exhaust tubes are usually comprised of an inner tube having the perforated region and an outer tube. Both tubes are connected to each other by washers welded to the tubes. The exhaust tubes must be sealed, otherwise the sound-absorbing properties of those tubes will be reduced. Therefore it is necessary during the manufacturing of these tubes to ensure that inner and outer tubes to be welded to each other be produced of the same length. Certain difficulties in the production of such tubes have occurred in practice.
Elongated sheet metal strips are utilized for making tubes with perforated portions. Perforations are usually formed at certain regions on the flat strip by a stamping tool. Then raster marks are formed at certain intervals on the blank to define the distances between the perforated regions and the edges of the finished tubes produced from the blank. These marks are formed by cutouts which extend transversal to the direction of elongation of the blank. These cutouts can be made simultaneously with making perforations on the tube blank to ensure that these cutouts are positioned at regular intervals between the perforated regions.
After the perforations and cutouts have been formed on the strip-like blank the latter is bent into a tube and an elongated weld seam is provided at the opposite edges of the bent tube. This process is named as a drawing-out method. This method results in stretching-out of the tube material. Due to such stretching-out round perforations made in the flat blank become oval and have, depending on the thickness and type of material, various dimensions so that the distance between the transversal cutout or mark and the edge of the perforation region on the finished tube is changed.
As mentioned above, perforated tubes are manufactured from the flat strip, then bent into the tubes and welded at the elongated edges. Then elongated tubes are cut into tube sections of the length of 6, 8, 10 or 12 m. During the cutting of each elongated tube piece into a plurality of tube sections, particularly in mass production, it is impossible to make a cut which would be accurate in the radial plane through which the mark or cutout extends. Even if the length of manufactured cut tube sections differs from a required one in a couple of millimeters, the tube sections should be thrown away as waste.
For cutting elongated tubes into sections by a saw blade relatively long tubes of 6 to 12 m are placed into a tube supply magazine. The tubes within the magazine are separated from each other and fed to feeding rollers which in cooperation with drive wheels lying on the tube transport the latter to the saw blade. The alignment of the tube to be cut with the saw by positioning the cutouts on the side of the tube opposite to the saw blade and by positioning the saw blade in the radial plane of the cutout has been carried out by hand. Such an alignment and adjustment of the tube and the saw by hand has been always difficult and required a high concentration and rationalization from a personnel. Moreover, such an adjustment carried out by hand caused a lot of waste due to the requirement that the perforated inner tubes of the exhaust tubes should have the same length as the outer tubes. Since no perforations and only marks have been required for the outer tubes the errors in the lengths of the inner tubes have been added to the errors in length of the outer tubes. Efforts have been made to manufacture inner and outer tubes of the same length with the least possible tolerances.
It has been necessary to meet those tolerances because the muffler is provided with further tubes which are connected to the motor vehicle at a precisely determined position.